This invention relates to a method and apparatus for the chemical treatment of plants, and more particularly to a method and apparatus for the dispersement of chemicals to plants through an existing irrigation system connected to a high pressure water supply line by a shutoff value and an antisiphon valve.
Public water systems require that an antisiphon valve be used to connect lawn sprinkling systems, and the like, to the water supply line in order to assure that no contamination of the public water system occurs due to back flow. The required antisiphon valve is commonly built into the shutoff valve. Consequently, any system for introducing chemicals may be connected only at the outlet of the shutoff valve and antisiphon valve unit.
The system for dispersing chemicals may be of the mixing-tank type disclosed in U.S. Pat. No. 3,351,290, but unless the plumbing is changed to introduce a throttling valve between two connections for the mixing tank, and thereby introduce the mixing tank at the outlet of a shutoff valve and antisiphon valve unit, the system cannot be used without violating standards of public water supply safety deemed necessary for the health of all users of the public water system. This precludes using the chemical treatment system in existing lawn or other sprinkling systems without modifying the plumbing.
Since most lawn irrigation systems in current use have an antisiphon valve connected very close to the shutoff valve, or built into the shutoff valve as a single unit, many lawn sprinkling installations cannot be easily modified to accommodate a chemical dispensing system due to clearance from structures, sidewalks, or other plumbing. It would be desirable to connect the chemical dispersing system to the irrigation system at the existing outlet pipe of the antisiphon valve and the existing inlet pipe of the shutoff valve. An object of this invention is to provide a method and apparatus for accomplishing that without violating standards of public water supply safety. Another object is to provide for flow rate control of the chemical being dispersed with a single valve adjustment and with only a pressure gauge.